Differential power analysis (DPA) is a powerful analytic technique that can be used to extract information about how circuits process data. Many circuits process data by performing a series of operations on the data. As part of performing these operations, the circuit draws power from an external power source in a manner that generates a power signature. This power signature can be used to isolate specific intermediate operations that comprise a data processing algorithm. By isolating these intermediate operations, a potential attacker can gain an understanding of how the data processing algorithm operates, and in some instances, by gaining this understanding, the attacker can potentially reverse engineer the circuit, or in some instances, extract and decrypt encrypted information from the circuit.
An attacker, in this context, may be an engineer trying to gain an understanding of how a competing product functions, but in some instances, an attacker may have even more sinister intentions. DPA can, for example, be used by attackers to extract cryptographic keys from cryptographic hardware by statistically correlating power consumption measurements (e.g., power signatures) recorded during processing of a cryptographic algorithm to specific intermediate operations of the cryptographic algorithm. The cryptographic hardware may, for example, be used to protect highly sensitive communications such as military communications or satellite communications. By isolating the specific intermediate operations that comprise the cryptographic algorithm, attackers can gain an understanding of how the cryptographic algorithm operates, and based on this understanding, the attackers can deconstruct the cryptographic algorithm incrementally until a cryptographic key can be successfully extracted. In some instances, even 128-bit and 256-bit encryption may be vulnerable to deconstruction via DPA.